This invention relates to a novel and improved yarn winding bobbin, as well as to a method for manufacturing the same in order to attain new and advantageous results in the practical use and respectively in manufacturing such bobbins.
More detailedly, this invention relates to a bobbin particularly suitable for winding coarse or thick yarns, i.e. high-count yarns, and essentially comprising a cylindric core and two flanges removably secured to both core ends. As it is well known, the bobbin flanges are removably secured to the bobbin core particularly when using bobbins wherein high count yarns are to be wound and wherein no danger exists that the yarn become clamped between the bobbin core ends and the flanges, due to removing and approaching movements of core and flange opposite normally contacting surfaces, as caused by the outside axially directed stresses exerted onto the flanges by the wound yarn in a full bobbin, and respectively by the flange resiliency in an empty bobbin. Obviously, when handling high count yarns, a given relative motion of said opposite core and flange surfaces is yet admissible, provided that no openings wider than the yarn diameter will formed under the greatest possible stresses.
Said removable flanges are usually fastened by means of screws to the core ends and are advantageous in that they may be easily and quickly replaced in cases of flange breakages. However, such flange replacement may involve drawbacks in particular for bobbins designed to operate on modern equipments running at high and very high speeds.
Indeed, a bobbin static and dynamic balancing operation is usually required, in particular when dealing with bobbins operating at high speeds. Such balancing operation is usually carried-out by inserting or securing one or more balancing weights to one or more bobbin flanges, at circumferentially selected and axially eccentric positions thereof. Obviously, when a broken flange is to be replaced, the previously performed balancing operation is no more effective and a new balancing operation ought to be made by the bobbin user, that however does not usually possess the necessary equipments.